The present invention broadly relates to a drive mechanism for fully automatic opening and closing of at least one sliding door and more specifically, for a sliding door which is movable with a greater speed on the initial and preferably major portion of the opening and closing path than on the terminal and preferably minor portion, and which is mobile by means of a coupling device.
For moving sliding doors it is known to the state-of-art to perform the major or initial portion of the sliding path with a greater speed than the remainder of the sliding path.
The reason for such variable movement of the door can be seen in the fact that the door should open very fast and, especially during the cold season, should also close rapidly. In order to avoid a collision of both parts of a double-wing or double-panel door, or that a single-wing or single-panel door collide excessively hard with a confronting wall, the closing speed is reduced in the minor or terminal part of the closing path.
Various drive mechanisms are used to provide such differential speeds. However, they all display numerous disadvantages. The use of pneumatic pistons (pneumatic drive) or hydraulic pistons (hydraulic drive) requires the availability of compressed air or pressurized oil, respectively, for which relatively great technical expenditure is required. In the first case the compressor causes undesirable noise, and in case of a hydraulic drive leaking oil can cause contamination.
Furthermore, various mechanical drives are known. For example, an electric motor can drive an open-link chain or a rubber chain, or toothed belt extending over the entire travel path of the door or door panel.
The regulation of the motor into slow revolutions and even to zero revolutions requires a great number of electronic components. In case of breakdown of the sensitive electronic control an expert from outside has to be called since the normal skilled service personnel does not have the knowledge necessary for repairing the damage.